This invention relates to jacking mechanism for moving a string of well pipe vertically within a well.
Jacking mechanisms embodying the invention are of a general type disclosed in several prior copending applications and especially adapted in certain respects for lowering a heavy string of casing through a wellhead and into a well after completion of the process of drilling the well. This jacking mechanism may include two units which are adapted to engage and support a pipe at different locations and power actuated means for moving one of those units upwardly and downwardly relative to the other to attain the desired jacking action. The power actuated means preferably take the form of two piston and cylinder mechanisms located at opposite sides of the well axis and positioned in the rig near the rotary table location.